1)
2) 0,38^2+1.42*0.38+1.8*4.62 = 0.38*(0.38+1.42)+1.8*4.62 = 0.38*1.8+1.8*4.62 = 1.8(0.38+4.62)=1.8*5=9
1)<1=90°-<2 ;BC_|_AD
<4=90°-<3
<2=<3;90°-<2=90°-<3
<1=<4
2)
<AOD=160°;OE биссектриса
<АОЕ=160°:2=80°
160°+<AOC=180°
<AOC=20°
<AOC=<BOD=20°
<ЕОД=<СОF=80°
<BOD=<AOC=20°
<AOF=<AOC+<COF=
80°+20°=100°
X²+3x=4
x²+3x-4=0
D=3²-4*(-4)*1=9+16=25=5²
Ответ: х₁=-4,х₂=1
a³-(a+1)³+3a²=a³-(a³+3a²+3a+1)+3a²=a³-a³-3a²-3a-1+3a²=-3a-1= -(3a+1)